We intend to investigate the possible developmental difference between male and female bovine embryos. Previous studies from our laboratory showed that male embryos develop faster that their female counterparts even before activation of embryonic genome. The main objective of this project is to examine possible developmental difference in male and female bovine embryos and the effect of oocyte's maturational status on this dimorphic pattern of development. To accomplish this, we will employ in vitro maturation and fertilization. Cultured embryos produced using sorted sperm will be monitored during their early development. Microtubule organization characteristics will be determined to interpret the maturational effect on development of male and female embryos. For this reason, we will employ immunostaining and confocal microscopy after fertilization. Understanding developmental patterns of male and female embryos provides valuable information on early development of bovine embryos. Although conventional fluorescence microscopy allows us to demonstrate localization of microtubule cytoskeleton it is limiting in terms of providing images that can be used to obtain quantitative and qualitative measurements. In another study in which we figured out cytoskeletal differences in embryos fertilized with sperm from different bulls, confocal microscopy allowed us to demonstrate these characteristics very clearly. From that point, we will use the same approach in this current study.